Balanced carbon pile



Jfily 28, 1959 A. 5. 5555); ET AL 2,897,466

BALANCED CARBON PILE Filed Nov. 25, 1956 2 Sheets-Sheet l INVENTORS AAO/S 51 ESS'X fZ/Vfl? E. GARRETT HENRY E Mckf/WWFY ATTORNEY 28, 19 59 7 I A. B. ESSEX ETAL 2,897,466

Filed Nov. 25, 1956 BALANCED CARBON FILE 1 2 Sheets-Sheet 2 INVENTORS A401: 5. ESSEX ATTORNEY United States Patent O BALANCED CARBON PILE Alois B. Essex, Glendale, and Ehner E. Garrett, Freeport,

N.Y., and Henry F. McKenncy, Weston, Mass, assignors to Sperry Rand Corporation, Ford Instrument Company Division, Long Island City, N.Y., a corporation of Delaware Application November 23, 1956, Serial No. 623,844

7 Claims. (Cl. 338- 105) This invention relates to variable resistance devices of the carbon pile type which are especially adapted for use in airplanes and guided missiles which are subjected to vibrations and rapid accelerations and decelerations.

Carbon pile rheostats of this character generally comprise a pile of carbon discs which are held under compression by the action of a spring diaphragm, and a solenoid which is operative when energized to relieve the spring pressure upon the pile of discs and thus control the pile resistance. The spring diaphragm has an armature rigidly secured thereto through which the solenoid acts to relieve the pressure exerted by the spring dia phragm upon the pile or discs, and adjusting means are provided by which the maximum pressure exerted by the diaphragm upon the pile of discs may be regulated as desired. When such a resistance device is axially accelerated in one direction, the armature, due to inertia, reacts to increase the pressure upon the carbon piles and thereby decrease the resistance of the pile; and when the device is accelerated in the opposite direction the armature reacts to decrease the pressure upon the carbon pile and thereby increase the resistance of the pile, the same reaction occurring after deceleration. This inherent characteristic of carbon pile resistance devices of this character render them objectionable for uses wherein they are subjected to axial vibrations and accelerations.

It is therefore the principal object of this invention to provide means in a carbon pile resistance device of the aforesaid character by which the vibration and acceleration effects upon the carbon pile are counteracted whereby the pile resistance is maintained constant under :all conditions of use.

One method of accomplishing this result is to apply a counterbalancing weight to the end of the carbon pile opposite the armature. With this arrangement when, .under acceleration, the armature decreases the pressure upon one end of the carbon pile the counterbalancing weight will proportionately increase the pressure upon the other end of the carbon pile and thereby maintain the compression of the carbon pile, and consequently 'the resistance thereof, constant under all conditions.

Another way of counteracting the acceleration effects upon a carbon pile resistance device of the aforesaid char- .acter is to provide a pivoted lever having a weight secured to the lower end thereof and having the upper .end thereof connected to the armature by suitable link- .age. With this arrangement the weighted lever will counteract the reaction of the armature upon the carbon pile during acceleration.

The principal object of the invention having been stated other and more specific objects of the invention will be apparent from the following specification and the accompanying drawings forming a part thereof wherein:

Fig. l is a central longitudinal section illustrating that form of the invention in which a counterbalancing weight is provided to counteract the reaction of the armature upon the carbon pile during acceleration;

Fig. 2 is a view similar to Fig. 1 illustrating one form of the invention in which a Weighted lever is provided Patented July 28, 1959 to counteract the reaction of the armature upon the carbon pile during acceleration; and

Fig. 3 is a View similar to Fig. 2 in which a soft diaphragm is provided only to carry the armature and in which the pressure upon the carbon pile is exerted by a spring through a pivoted weighted lever and a connecting link between the upper end of the lever and the armature and in which the weighted lever is also operative to counteract the reaction of the armature upon the carbon pile during acceleration.

The various forms of the invention shown in the drawings will now be specifically described in detail with the use of reference numerals, the same numerals being applied to like parts in the difierent forms of the invention shown.

Referring first to Fig. l of the drawings the numeral 1 indicates generally a conventional rheostat of the carbon pile type which comprises a casing 5 provided with heatdissipating fins 6. A pile 7 of carbon discs is mounted in an open-ended tube 3 which is disposed in a longitudinally extending axial bore 9, in the casing 5 and which communicates at the inner end thereof with an enlarged annular chamber 19 at one end of the casing 5. A spring diaphragm it which is suitably secured in fixed position in the chamber 10 has secured to one side thereof a button 12 which is adapted to engage one end of the carbon pile 7, and to the other side thereof an armature 13 which coacts with a solenoid 14 which is also secured in fixed position in the chamber 10. The carbon discs in the pile 7 are held under compression by the spring diaphragm ll acting through the button 12; and the pressure exerted by the diaphragm 11 upon the carbon pile 7 is regulated by an adjusting screw 15 disposed adjacent the opposite end of the carbon pile in a removable closure plate 16 which closes the outer end of the bore 9. The solenoid 14 is of conventional construction and com.- prises the winding 17 and the core 13 which is carried by the closure plate 19, of the chamber 10, in axial alignment with the armature 111 and carbon pile 7. When the solenoid 14 is energized the core 18 attracts the armature 13 which reduces the compression of the pile 7 and thereby increases the resistance of the pile 7 to the flow of current therethrough.

When the rheostat 1 is accelerated to the right as shown in Fig. l, the armature 13, due to inertia, will react to decrease the pressure exerted by the spring diaphragm 11 upon the carbon pile and thereby increase the resistance thereof; and when the rheostat is accelerated to the left the armature 13 will react to increase the pressure upon the carbon pile and thereby decrease the resistance thereof.

In order to counteract the reaction of the armature 13 upon the carbon pile 7 during acceleration and deceleration and thereby maintain the resistance of the rheostat 1 constant under all conditions, I provide a weight 21 and a compression spring 22 which are interposed between the pressure adjusting screw 15 and the adjacent end of the carbon pile 7. The weight 21 and spring 22 are disposed in a cylindrical chamber 23 in the cap 16 which constitutes an elongation of the axial bore 9 in the casing 5. During acceleration and deceleration the reaction of the weight '21 upon one end of the carbon pile 7 will be equal and opposite to the reaction of the armature 13 upon the opposite end of the carbon pile 7. The resistance of the carbon pile 7 will therefore always be maintained constant during acceleration and deceleration.

In the form of the invention shown in Fig. 2 the core 18 of the solenoid 14 is provided with an axial bore 25. In order to counteract the reaction of the armature 13 upon the carbon pile 7 during acceleration and deceleration in this form of the invention a lever 26 iS pivotally secured intermediate the ends thereof as indicated at 27 to a bracket 28 carried by the closure plate 19. The upper end of the lever 26 is pivotally connected to the armature 13 by a link 29 which extends through the bore 25 in the core 18; and a weight 30 is secured to the lower end of the lever 26. During acceleration and deceleration the weight 30 counteracts the reaction of the armature 13 upon the carbon pile 7 and thereby maintains the resistance of the carbon pile constant.

Fig. 3 discloses another form of the invention which is similar to the form of the invention shown in Fig. 2. In this form of the invention a soft diaphragm 11a is substituted for the spring diaphragm 11 of Fig. 4, and the carbon pile 7 is held under compression by a spring 31 which is connected to the lever 26 adjacent the lower end thereof. Otherwise this form of the invention is identical with that shown in Fig. 2 and as in Fig. 2 the weight 30 counteracts the reaction of the armature 13 upon the carbon pile 7 during acceleration and deceleration, and thereby maintains the resistance of the carbon pile 7 constant.

From the foregoing it will be apparent to those skilled in this art that we have provided very simple and efficient means for accomplishing the objects of the invention; and although the solenoid is shown and described herein as operative when energized to decrease the compressive pressure upon the carbon pile and thereby increase the resistance thereof, it is to be understood that the invention contemplates the reverse action of the solenoid where in the solenoid is operative when energized to increase the compressive pressure upon the carbon pile and there by decrease the resistance thereof.

And it is to be further understood that we are not limited to the specific constructions shown and described herein as various modifications may be made therein within the spirit of the invention and the scope of the appended claims.

We claim:

1. A variable resistance mechanism of the character described for use on vehicles subjected'to rapid accelerations and decelerations, said mechanism comprising a carbon pile, a spring diaphragm by which a compressive pressure is exerted upon one end of said carbon pile, an armature secured to said diaphragm in axial alignment with' said' carbon pile, spring means by which pressure is exerted uponthe other end of said carbon pile in opposition to the pressure exerted by said spring diaphragm, a freely floating counterbalancing shiftable weight interposed between said spring means and the said other end of said carbon pile in axial alignment with said carbon pile and said armature, a solenoid disposed in axial alignment with said armature and said carbon pile and operative whenenergized to attract said armature and thereby decrease the compressive pressure exerted upon said carbon 'pile, said counterbalancing weight being operative to counteract the reaction of said armature against saidcarbon pile due to acceleration of said variable resistance mechanism, the reaction of said weight against said carbon pile due to acceleration being equal "and opposite to the reaction of said armature.

2. A variable resistance mechanism of the character described for use on vehicles subjected to rapid accelerations and decelerations, said mechanism comprising a carbon pile, a solenoid disposed in axial alignment with said carbon pile, a shiftable'armature interposed between said solenoid and said carbon pile, spring means by which said armature is yieldingly forced into engagement with one end of said carbon pile to apply a predetermined compressive force to said carbon pile, said solenoid being operative when energized to attract said armature away from said carbon pile against the 'counteracting force of said spring means to thereby reduce the compressive force exerted upon said carbon pile, and a freely floating counterbalancing shiftable weight operatively associated with said armature by which the reaction of said armature upon said carbon pile due to acceleration of said mechanism is counteracted, the reaction of said counterbalancing weight, due to acceleration, upon said carbon pile, being equal and opposite to the reaction of said armature upon said carbon pile.

3. A variable resistance mechanism as defined by claim 2 in which said spring means comprises a spring diaphragm to which said armature is secured.

4. A variable resistance mechanism as defined by claim 3 in which said counterbalancing weight is disposed in engagement with the end of said carbon pile opposite said one end and in axial alignment with said carbon pile and said armature.

5. A variable resistance mechanism of the character described for use on vehicles subjected to rapid accelerations and decelerations, said mechanism comprising a carbon pile, a solenoid disposed in axial alignment with said carbon pile, a shiftable armature disposed between said solenoid and said carbon pile in contact with one end of said carbon pile, spring means by which said armature is yieldingly forced into engagement with said one end of said carbon pile to apply a predetermined compressive force to said carbon pile, said solenoid being operative when energized to attract said armature away from said carbon pile against the counteracting force of said spring means to thereby reduce the cornpressive force exerted upon said carbon pile through said armature, a lever pivotally supported between the ends thereof, a link interposed between the upper end of said lever and said armature, a freely floating counterbalancing shiftable weight secured to the lower end of said lever, said counterbalancing Weight being operative to counteract the reaction of said armature upon said carbon pile due-to acceleration of said variable resistance mechahism, the reaction of said counterbalancing Weight, due to acceleration of said mechanism, upon said carbon pile being equal and opposite to the reaction of said armature upon said carbon pile due to acceleration of said mechanism.

6. A variable'resistance mechanism as defined by claim 5 in which said spring means comprises a spring diaphragm to which said armature is secured.

7. A variable resistance mechanism of the character described for use on vehicles subjected to rapid accelerations and decelerations comprising a carbon pile, a solenoid disposed in axial alignment with said carbon pile, a shiftable armature interposed between said carbon pile and said solenoid in contact with one end of said carbon pile, a lever pivotally supported intermediate the ends thereof, a link interposed between the upper end of said lever and said armature, spring means operative through said lever and said link to yieldingly force said armature into engagement with the said one end of said carbon pile to apply a compressive force to said carbon pile, said solenoid being operative when energized to attract saidarmature away from said carbon pile against the counter force of said spring means to thereby reduce the compressive force exerted upon said carbon pile by said spring means, a freely floating counterbalancing shiftable weight secured to the lower end of said lever, said weight being operative to counteract the reaction of said armature, due to' acceleration of said variable resistance mechanism, upon said'carbon pile, the reaction of said counterbalancing weight, due to acceleration, upon said carbon pile being equal and opposite to the reaction of said armature.

References Cited inthe file of this patent 'UNITED STATES PATENTS 1,417,151 Donop May 23, 1922 2,203,061 Schmettow June 4, 1940 "2,441,059 Creveling May 4, 1948 2,759,157 Wiancko Aug. 14, 1956 2,767,584 Franzel et al Oct-23, 1956 v 'FOREIGN PATENTS 457,337 Great Britain Nov. 25,- 1936 

